Due to development of scientific techniques, improvement of quality and convenience of living, use of disposables has rapidly increased. Particularly, paper coated with polymers such as polyethylene (PE) has bee used in various disposable container fields. General polyethylene coated paper is manufactured by extrusion coating polyethylene on one surface or both surfaces of paper. For this reason, the polyethylene coated paper commonly refers to paper serving to prevent outflow of contents and absorption of moisture.
The polyethylene coated paper has excellent water-barrier property to block contents from moisture. However, in the case in which a container is made of a polyethylene paper, the paper has low oxygen-barrier property, such that the contents therein may be oxidized to thereby become rotten. Therefore, in order to prevent food from being oxidized, being rotten, or the like, due to contact with oxygen and enable long-term preservation, aluminum coating layer is introduced to improve the oxygen-barrier property such as Tetra-Pak, or Nylon coating, ethylene vinyl alcohol copolymer (EVOH) coating, or the like, is performed. However, introduction of the aluminum coating layer has economical disadvantages in that aluminum is an expensive material and an expensive process is required, and the Nylon coating and EVOH coating have economical disadvantages in that Nylon and EVOH are also expensive and an additional adhesive layer is required.
In addition, polyethylene, which is a representative non-polar resin, is insufficient in terms of printability, which is importantly required as a material for packaging. Further, since polyethylene has low adhesion with the paper due to non-polarity, in order to improve the adhesion with the paper, polyethylene is extruded at a high temperature of 300 to 350° C. to be thermally oxidized, such that the thermal oxidized polyethylene should be coated on the paper while inducing polar groups on a melted surface thereof.
In addition, in the polyethylene coated paper container used for foods, a coating surface thereof may be deformed or damaged when the polyethylene coated paper container is used in a microwave oven having high power.
Therefore, coated paper having excellent oxygen barrier property, good printability, and high thermal stability has been required.